Fibrous sheet material and process of making same



Patented Nov. 11, 1930 UNITED STA res PATENT OFFICE JAMES C. PEABODY,BOSTON, AND ALFRED BROWN, OF EVERETT, MASSACHUSETTS; E. LOUISE PEABODY,EXECUTBIX OF SAID JAMES C. PEABODY, DECEASED, ASSIGN- ORS, BY DIRECT ANDMESNE ASSIGNMENTS, TO FRANK B. HOPEWELL, OF NEWTON,

MASSACHUSETTS, AS TRUSTEE FIBROUS SHEET MATERIAL AND PROCESS OI! MAKINGSAME No Drawing. I Application filed July 23,

This invention relates to the art of making fibrous sheet material of apaper-like nature and to the-resulting product.

" The object of the invention is to produce by treating naturalvegetable cellulose fibres, such as those of hemp, ramie, cottonandwood, a paper-like sheet material suitable for a large variety ofpurposes where strength is required such as material for innersoles andreinforcements for shoes, such as a base for artificial leather andwhich is capable of being molded into a wide variety of forms and which,after it has once been dried, will not disintegrate when immersed inwater.

The object of the inventiori is further to produce such a material'whichshall be and remain flexible and soft.

The object of the invention is further and more particularly to producerapidly and economically a paper-like material from wood pulp fibrehaving the foregoing characteristics.

These and other objects and features of the invention will a pearmorefully from 2 the accompanying. escription and will be particularlypointed out in the claims.

The important feature of this invention resides in the chemicaltreatment of natural cellulose vegetable fibres to bring them into aswollen gelatinous state insoluble in water or dilute caustic soda. Suchtreated fibres are then used, preferably mixed with untreated fibres, inthe manufacture of paper or sheet material by processes of a typeusually employed in the manufacture of ordinary paper.

The natural vegetable cellulose fibres may be obtained from a variety ofmaterials such as hemp, ramie, cotton and wood pulp. But the inventionis particularly useful in connection with wood pulp and that fibre is employed in disclosing the preferred form of 1929. Serial No. 380,456.

pressed to about three times the weight of I the' original cellulosefibre. The soda cellulose thus formed is allowed to age for about threedays. The soda cellulose is then treated for about four or five hourswith carbon disulphide in amount about equal to half the weight of theoriginal cellulose fibre to form what is .known as cellulose xanthate.Cellulose Xanthate is completely soluble in water or dilute caustic sodafrom which it may be regenerated in the form of rayons, films, etc.

The present invention depends upon the discovery that by properlycorrelating (1) the proportion of the alkali such as caustic soda, (2)the proportion of carbon disulphide, (3) the time of treatment withcarbon disulphide, and (4) the temperature at which the reaction iscarried on, an incomplete conversion of the fibres into cellulosexanthate. may be effected so as to leave the fibres in a swollengelatinous state, and characterized by being insoluble in water ordilute caustic soda; Either or all of these factors may be varied withinlimits to produce the desired results. The reduction in the proportionsof the alkali and of the carbon disulphide in the solution below thosecommonly employed in the viscose process, the reduction'in the length oftime of the treatment particularly with carbon disulphide, and decreasein the temperature at which the reaction is carried on all tend toproduce the desired result of incomplete conversion of the fibres intocellulose xanthate. Consequently, by varying one, any or all of thesefactors in accordance with this principle, a correlation thereof. may beeffected to secuie the desired result.

For example, the following process has .been found satisfactory. A givenweight of dry wood pulp fibre is treated for one hour with a 10%solution of caustic soda at room temperature or substantially 60 F. to90 F. The stock is then whizzed in a centrifuge or pressed in ahydraulic press to reduce it to about three times the weight of .theoriginal fibre. Carbon disulphide, equal in weight to about one-quarterof the weight of the original fibre, is then added to the stock inamplei a suitable container and the mixture agitated for several minutesand then allowed to stand for about one hour. This is found to effect anincomplete conversion of the fibres into cellulose xanthate and to leavethe fibres in a swollen gelatinous state and insoluble in water ordilute caustic soda. It Will be observed that, in this correlation ofthe various factors, the time of the reaction and the proportions of thealkali and of the carbon disulphide have been materially reduced belowthose referred to as employed in the ordinary viscose process, while thetemperature of the reaction is retained at normal room temperature.

Again it has been found that the proportions of the alkali in thesolution, as, for ex- 17 of caustic soda and carbon disulp iide equal toone-half the weight of the-fibre may be retained as in the viscoseprocess and the desired results secured by substantial reduction in thelength of time of the treatment as from the five hours commonly employedto one-half hour at room temperature. Again if the proportion of carbondisulphide be materially reduced, this will besuflicient, the otherfactors remaining substantially the same as in the viscose process.Again it has been found that the time of the reaction may be increasedif the proportion of carbon disulphide employed has been materiallyreduced. For example, if one-fourth of the weight of carbon'disulphideemployed in the viscose process be used, the length of time of thereaction may be slightly increased.

The various factors may therefore be varied so long as they are allbrought into such a correlation as to effect an incomplete co nversionof the fibres into cellulose xanthate and leave the fibres in a swollengelatinous state and insoluble in water or dilute caustic soda,characteristics which are readily ascertainable by inspection and thesimple test as to insolubility.

The fibres resulting from the foregoing treatment in accordance with theprinciple of this invention may then be employed for the manufacture ofpaper according to the usual processes, as, for example, by first beingmixed with water in a beater 0r rod mill to form the stock and, second,by reducing this stock to sheet form as through the operation of aFourdrinier machine.

It will be found that the time required toproduce the stock in thebeater or rod mill is very much less than when the stock is made fromuntreated fibres and, further, it will be found that the stock producedfrom the treated fibre of this invention is much more free thanuntreated fibre, that is, the water drains faster from the treated fibrewhen it is run over the Fourdrinier machine.

But the best results are secured and at less expense by mixing thetreated fibre of this invention with untreated fibre in the beater orrod mill to form the stock and preferably in about equal proportions.But in either event, it will be found that a much less time is requiredto produce the stock with the treated fibre in a heater or rod mill.

The sheet material or paper has marked advantages and characteristics.It is of great strength and toughness and this strength may beconsiderably increased by prolonging the beating action in the formationof the stock in the beater or rod mill.

The material does not disintegrate, after it has once been dried, whenimmersed or soaked in water and even then retains considerable strength.

The material is suitable for many purposes, includin inner soles andreinforcements for shoes, aliase to receive the various coatingsemployed in the manufacture of artificial leather, and those purposes towhich a wide variety of woven and fibrous sheet materials haveheretofore been employed. The material is readily moldable before it isdried or when moistened into various shapes and forms.

While caustic soda is preferably employed, it will be understood that,with suitable variations familiar to those skilled in the art, causticpotash may be employed.

The material, either during the process of the mixing of the stock orits formation in sheet form or afterward, may be treated with varioussubstances to produce particular desired results. One desired resultwhich may thus be produced is to make the sheet material more flexibleby the addition of glycerin or a similar substance. For this purposeglycerin may be either added in the beater in the mixing of the stock orthe finished sheet material may be soaked in a glycerin solution. Themain characteristic of glycerin which secures the desired result is thatit is hygroscopic and acts to retain sufficient moisture in the paper torender it soft and flexible, although glycerin itself has some softeningeffect. Any suitable hygroscopic softening agent may therefore beemployed in lieu ofglycerin for this purpose. A 5% solution of glycerinis found desirable when the paper is soaked therein.

From the foregoing disclosure of the prin ciples of this invention andspecific applications of these principles, one may readily treat naturalvegetable cellulose fibres to bring them to a swollen gelatinous stateinsoluble in water or dilute caustic soda and make therefrom, eitheralone or mixed with untreated fibre; a sheet or paper-like materialhaving the desired characteristics.

Having thus described the invention, what is claimed as new, and desiredto be secured by Letters Patent, is:

1. The process of treating natural vegetable cellulose fibres whichconsists in treating the fibres with caustic soda and carbon disulphideand water after the manner of cellulose xanthate, as to effect only anincom- K the viscose process, but with the Proportions of said reagentsto the water so reduced, beyond those normally employed at theprevailing temperature to convert the fibres into caustic soda.

3. The process which consists in treating natural vegetable cellulosefibres with caustic soda, carbon disulphide and water to produce anincompleted cellulose xanthate condition and to leave the fibres swollenand gelatinous and insoluble in water or dilute caustic soda.

4. The process of treating natural vegetable cellulose fibres whichconsists in incompletely converting the fibres into cellulose xanthateto render the fibres swollen, gelatinous and insoluble in water ordilute caustic soda. K

5. The rocess of making a fibrous sheet material f i'om wood pulp whichconsists in treating a quantity of substantially dry wood pulp with a10% solution of caustic soda for one hour at a temperature of from to 90F., in mechanically removing the liquid in the stock so produced toreduce the stock to a weight about three times that of the originalquantity of wood pulp, in adding to the stock carbon disul hide of aweight of about one-fourth that o? the original quantity of wood pulp,inagitating the stock for several minutes, in allowing the stock tostand for about an hour, in mixing the stock with an equal quantity ofordinary Wood pulp stock, and in beating the mixture thoroughly andforming into sheet form by methods usually employed in paper making.

6. The process of making fibrous sheet material which consists intreating wood pulp according to the process defined in claim 1, in thenmixing the stock with ordinary wood pulp stock, and in beating themixture thoroughly and forming the same into sheet material by methodsusually employed in paper' making.

'7. The process of making fibrous sheet material which consists intreating wood pulp terial by methods usually employed in paper making.

8. The process of making fibrous sheet material which consists inincompletely con-- verting natural vegetable cellulose fibres intocellulose xanthate to render the fibres swollen, gelatinous andinsoluble inivat'er or dilute caustic soda, in mixing therewithuntreated natural vegetable cellulose fibres in water to form a stock,in beating the stock thoroughly and forming into sheet form by methodsusually employed in paper making.

9. The process of making fibrous sheet material which consists intreating wood pulp according to the process defined in claim 1, in thenmixing the stock with ordinary wood pulp stock, in beating the mixturethoroughly and forming the same into sheet material by methods usuallyemployed in paper making,

and in soaking the sheet material in a solution of a suitablehygroscopic softening agent to render the material soft and flexible.

10. The process of making fibrous sheet material which consists intreating wood pulp according to the process defined in claim 1, in thenmixing the stock with ordinary wood pulp stock, in beating the mixturethoroughly and forming the same into sheet material by methods usuallyemployed in paper making, and in soaking the sheet material in a 5%solution of glycerin to render the material soft and fiexibl'e.

. 11. The process of making fibrous sheet material which consists inincompletely convex-ting natural vegetable cellulose fibres intocellulose xanthate to render the fibres swoling the same into sheetmaterial by methods usually employed in paper manufacture.

13. The process of making fibrous sheet material which consists inincompletely converting natural vegetable cellulose fibres intocellulose xanthate to render the fibres swollen. gelatinous andinsoluble in water or dilute caustic soda, in forming the same into astock, in beating the stock thoroughly and forming into sheet form bymethods usually employed in paper making.

14. A swollen, gelatinous vegetable fibre incompletely converted intocellulose xanthate and insoluble in water or dilute caustic soda.

15. A sheet of fibrous material composed of natural vegetable fibresmixed with swollen, gelatinous vegetable fibres incompletely convertedinto cel ulose xanthate and insoluble in water or dilute caustic soda.

16. A sheet of paper-like material com posed of natural wood fibres andwood fibres previously treated to present'a swollen, elatinous conditioninsoluble in water or di ute caustic soda.

17. A sheet of fibrous material comprising swollen, gelatinous vegetablefibres incompletely converted into cellulose xanthate and insoluble inWater or dilute caustic soda.

18. A sheet of fibrous material composed of natural vegetable fibresmixed with swollen, gelatinous vegetable fibres incompletely convertedinto cellulose xanthate and insolu ble in water or dilute caustic sodaand containing glycerin to render the sheet soft and flexible.

19. A sheet of pa er-like material composed of natural woo fibres andwood fibres previously treated to present a swollen, gelatinouscondition insoluble in water or dilute n caustic soda and containinglycerin to render the sheet soft and flexi le.

20. A sheet of fibrous material comprising swollen, gelatinous vegetablefibres incompletely converted into cellulose xanthate and an insolublein water or dilute caustic soda and containing glycerin to render thesheet soft and flexible.

In testimony whereof, we have signed our names to this specification..i- JAMES C. PEABODY.

ALFRED BROWN.

